Evaluation of nitrogen- and silicon-vacancy defect centres as single photon sources in quantum key distribution

We demonstrate a quantum key distribution (QKD) testbed for room temperature single photon sources based on defect centres in diamond. A BB84 protocol over a short free-space transmission line is implemented. The performance of nitrogen-vacancy (NV) as well as silicon-vacancy defect (SiV) centres is evaluated and an extrapolation for next-generation sources with enhanced efficiency is discussed.Comment: 14 pages, 5 figure

The complexity of probabilistic EL

We analyze the complexity of subsumption in probabilistic variants of the description logic EL. In the case where probabilities apply only to concepts, we map out the borderline between tractability and EXPTIME-completeness. One outcome is that any probability value except zero and one leads to intractability in the presence of general TBoxes, while this is not the case for classical TBoxes. In the case where probabilities can also be applied to roles, we show PSPACEcompleteness. This result is (positively) surprising as the best previously known upper bound was 2-EXPTIME and there were reasons to believe in completeness for this class

Effect of tapentadol on neurons in the locus coeruleus

Tapentadol is a novel centrally acting drug that combines mu-opioid receptor (MOR) agonism and noradrenaline reuptake inhibition (NRI), producing analgesic effects in various painful conditions. We investigated the acute effects of tapentadol in the locus coeruleus (LC), a central nucleus regulated by the noradrenergic and opioid systems that is critical in pain modulation. In single-unit extracellular recordings of LC neurons from anaesthetized male SpragueeDawley rats, tapentadol clearly inhibited the spontaneous electrophysiological activity of LC neurons in a dose-dependent manner (ED50 ¼ 0.8 mg/kg). This inhibitory effect was reversed by RX821002 (an alpha2-adrenoceptor antagonist) and naloxone (a mu-opioid receptor antagonist) by 96.7% and 28.2%, respectively. Pretreatment with RX821002, Nethoxycarbonyl- 2-ethoxy-1-2-dihydroquinoline (EEDQ, an irreversible alpha2-adrenoceptor antagonist) or naloxone shifted the tapentadol doseeeffect curve to the right (ED50 ¼ 2.2 mg/kg, 2.0 mg/kg and 2.1 mg/kg, respectively). Furthermore, tapentadol inhibited the LC response to mechanical stimulation of the hindpaw in a dose-dependent manner. In summary, we demonstrate that acute administration of tapentadol inhibits LC neurons in vivo, mainly due to the activation of alpha2-adrenoceptors. These data suggest that both the noradrenergic and opioid systems participate in the inhibitory effect of tapentadol on LC neurons, albeit to different extents, which may account for its potent analgesic effect and mild opioidergic side-effects.This study was supported by grants from Grünenthal GmbH (OT2010/075); “Fondo de Investigación Sanitaria” (PI10/01221 and PI12/00915); CIBERSAM (G18); Junta de Andalucía, Consejería de Innovación, Ciencia y Empresa (CTS-510, CTS-4303 and CTS-7748); Cátedra Externa del Dolor Grünenthal-Universidad de Cádiz; FP7-PEOPLE-2010-RG (268377); FPU (AP2007-02397) and FPI (2011-145) fellowship

Field observational constraints on the controllers in glyoxal (CHOCHO) reactive uptake to aerosol

Glyoxal (CHOCHO), the simplest dicarbonyl in the troposphere, is a potential precursor for secondary organic aerosol (SOA) and brown carbon (BrC) affecting air quality and climate. The airborne measurement of CHOCHO concentrations during the KORUS-AQ (KORea–US Air Quality study) campaign in 2016 enables detailed quantification of loss mechanisms pertaining to SOA formation in the real atmosphere. The production of this molecule was mainly from oxidation of aromatics (59 %) initiated by hydroxyl radical (OH). CHOCHO loss to aerosol was found to be the most important removal path (69 %) and contributed to roughly ∼ 20 % (3.7 µg sm−3 ppmv−1 h−1, normalized with excess CO) of SOA growth in the first 6 h in Seoul Metropolitan Area. A reactive uptake coefficient (γ) of ∼ 0.008 best represents the loss of CHOCHO by surface uptake during the campaign. To our knowledge, we show the first field observation of aerosol surface-area-dependent (Asurf) CHOCHO uptake, which diverges from the simple surface uptake assumption as Asurf increases in ambient condition. Specifically, under the low (high) aerosol loading, the CHOCHO effective uptake rate coefficient, keff,uptake, linearly increases (levels off) with Asurf; thus, the irreversible surface uptake is a reasonable (unreasonable) approximation for simulating CHOCHO loss to aerosol. Dependence on photochemical impact and changes in the chemical and physical aerosol properties “free water”, as well as aerosol viscosity, are discussed as other possible factors influencing CHOCHO uptake rate. Our inferred Henry's law coefficient of CHOCHO, 7.0×108 M atm−1, is ∼ 2 orders of magnitude higher than those estimated from salting-in effects constrained by inorganic salts only consistent with laboratory findings that show similar high partitioning into water-soluble organics, which urges more understanding on CHOCHO solubility under real atmospheric conditions

Secondary organic aerosol production from local emissions dominates the organic aerosol budget over Seoul, South Korea, during KORUS-AQ

Organic aerosol (OA) is an important fraction of submicron aerosols. However, it is challenging to predict and attribute the specific organic compounds and sources that lead to observed OA loadings, largely due to contributions from secondary production. This is especially true for megacities surrounded by numerous regional sources that create an OA background. Here, we utilize in situ gas and aerosol observations collected on board the NASA DC-8 during the NASA–NIER KORUS-AQ (Korea–United States Air Quality) campaign to investigate the sources and hydrocarbon precursors that led to the secondary OA (SOA) production observed over Seoul. First, we investigate the contribution of transported OA to total loadings observed over Seoul by using observations over the Yellow Sea coupled to FLEXPART Lagrangian simulations. During KORUS-AQ, the average OA loading advected into Seoul was ∼1–3 µg sm−3. Second, taking this background into account, the dilution-corrected SOA concentration observed over Seoul was ∼140 µgsm−3ppmv−1 at 0.5 equivalent photochemical days. This value is at the high end of what has been observed in other megacities around the world (20–70 µgsm−3ppmv−1 at 0.5 equivalent days). For the average OA concentration observed over Seoul (13 µg sm−3), it is clear that production of SOA from locally emitted precursors is the major source in the region. The importance of local SOA production was supported by the following observations. (1) FLEXPART source contribution calculations indicate any hydrocarbons with a lifetime of less than 1 day, which are shown to dominate the observed SOA production, mainly originate from South Korea. (2) SOA correlated strongly with other secondary photochemical species, including short-lived species (formaldehyde, peroxy acetyl nitrate, sum of acyl peroxy nitrates, dihydroxytoluene, and nitrate aerosol). (3) Results from an airborne oxidation flow reactor (OFR), flown for the first time, show a factor of 4.5 increase in potential SOA concentrations over Seoul versus over the Yellow Sea, a region where background air masses that are advected into Seoul can be measured. (4) Box model simulations reproduce SOA observed over Seoul within 11 % on average and suggest that short-lived hydrocarbons (i.e., xylenes, trimethylbenzenes, and semi-volatile and intermediate-volatility compounds) were the main SOA precursors over Seoul. Toluene alone contributes 9 % of the modeled SOA over Seoul. Finally, along with these results, we use the metric ΔOA/ΔCO2 to examine the amount of OA produced per fuel consumed in a megacity, which shows less variability across the world than ΔOA∕ΔCO

Searches at HERA for Squarks in R-Parity Violating Supersymmetry

A search for squarks in R-parity violating supersymmetry is performed in e^+p collisions at HERA at a centre of mass energy of 300 GeV, using H1 data corresponding to an integrated luminosity of 37 pb^(-1). The direct production of single squarks of any generation in positron-quark fusion via a Yukawa coupling lambda' is considered, taking into account R-parity violating and conserving decays of the squarks. No significant deviation from the Standard Model expectation is found. The results are interpreted in terms of constraints within the Minimal Supersymmetric Standard Model (MSSM), the constrained MSSM and the minimal Supergravity model, and their sensitivity to the model parameters is studied in detail. For a Yukawa coupling of electromagnetic strength, squark masses below 260 GeV are excluded at 95% confidence level in a large part of the parameter space. For a 100 times smaller coupling strength masses up to 182 GeV are excluded.Comment: 32 pages, 14 figures, 3 table

Multi-Jet Event Rates in Deep Inelastic Scattering and Determination of the Strong Coupling Constant

Jet event rates in deep inelastic ep scattering at HERA are investigated applying the modified JADE jet algorithm. The analysis uses data taken with the H1 detector in 1994 and 1995. The data are corrected for detector and hadronization effects and then compared with perturbative QCD predictions using next-to-leading order calculations. The strong coupling constant alpha_S(M_Z^2) is determined evaluating the jet event rates. Values of alpha_S(Q^2) are extracted in four different bins of the negative squared momentum transfer~\qq in the range from 40 GeV2 to 4000 GeV2. A combined fit of the renormalization group equation to these several alpha_S(Q^2) values results in alpha_S(M_Z^2) = 0.117+-0.003(stat)+0.009-0.013(syst)+0.006(jet algorithm).Comment: 17 pages, 4 figures, 3 tables, this version to appear in Eur. Phys. J.; it replaces first posted hep-ex/9807019 which had incorrect figure 4